From The White House

WASHINGTON, D.C. — United States President Barack Obama will take the oath of office twice – once on Sunday and once on Monday – to satisfy both the US constitution as well as the public need to witness it.
He will be formally sworn into office on Sunday in keeping with the dictates of the constitution, which mandates the previous presidential term ends at noon on January 20. That ceremony will take place at a small gathering at the White House.
But by tradition, if January 20 falls on a Sunday, the public swearing in on the steps of the Capitol is delayed to another day of the week – in this case, until Monday.
It will be the seventh time in history that the public inauguration has been delayed due to a Sunday end-of-term.
And for Obama, it will be the second time he will have been sworn in twice, the first time owing to a glitch in the public event on January 20, 2009 when Chief Justice John Roberts switched around some of the words and used a ''to'' instead of an ''of'' at one point. To ensure there would be no question that the swearing in was done correctly, Obama was sworn in a second time the following day.
The tradition of no public ceremony on a Sunday dates back to 1821, the first time the inauguration fell on a Sunday.
Then-president James Monroe decided after consulting with the Supreme Court to postpone the public ceremony until the next day because ''courts and other public institutions were not open on Sunday.''
Technically, that meant the country had no legal president for a day - as happened again in 1849, when president Zachary Taylor delayed the public affair for a day. That case gave rise to a myth about the top-ranked senator, David Rice Atchison, who was declared by many - including a recently opened museum in his home state of Kansas and his own tombstone - to have been president for a day by default.
Atchison himself never made that claim, telling a St Louis, Missouri, newspaper that he was never sworn as president and in fact had slept away the day, March 4, 1849, on which the previous president's term had expired.
''There had been three or four busy nights finishing up the work of the Senate, and I slept most of that Sunday,'' Atchison is quoted as having said.
Since then, four other presidents - Rutherford B Hayes (1877); Woodrow Wilson (1917); Dwight D Eisenhower (1957); and Ronald Reagan (1985) - have delayed the public ceremony to a Monday.
But all four took the precautionary measure of a private swearing in on the actual date their terms ended, as will Obama on Sunday.
US presidents also have a tradition of swearing in on a Bible.
On Sunday, Obama will lay his hand on the family Bible of his wife Michelle's grandmother, the inaugural committee said.
On Monday, he will use two Bibles stacked together: a black King James Bible that slain civil rights leader Martin Luther King Jr carried on his travels and a burgundy velvet Bible used by president Abraham Lincoln at his first inauguration.
The choices reflect not only the historic significance of the country's first black president beginning his second term, but also the fact that January 21 is a national holiday commemorating King.
The January 20 inaugural date was established by the 20th Amendment to the constitution, which until 1933 specified March 4 as the end of term. The move shortened the lame-duck nature of the government after November elections.